The present invention is concerned with a method and apparatus for applying a deicer liquid to frozen water on a ground surface and, in particular, with applying a deicer liquid to frozen water on roadways or any other surface from which it is desired to remove the frozen water.
It is, of course, a common practice of long standing to apply salt (NaCl), usually in the form of rock salt, or calcium chloride (CaCl.sub.2) in pellet or flake form to snow, ice, or the like in order to soften it to facilitate removal of the thus-softened snow, etc. by mechanical means. The salt or calcium chloride lowers the melting temperature of the frozen water causing the areas on which the salt is applied to melt.
There are several shortcomings to this approach, not the least of which is the concern for environmental damage due to tonnage quantities of salt or calcium chloride being applied to roads and highways and ultimately finding its way into adjacent fields and streams. Further, the salt is corrosive and adversely affects vehicles, metal fixtures such as fence rails and light posts adjacent the highways and the concrete itself. In addition, a crystalline material such as salt is inert as a deicer until it has been dissolved. This requires contact with moisture. The moisture, acting as a solvent, will dissolve the salt particles and the resultant brine is the active deicing agent. The speed at which the inert crystalline material becomes an active deicer is thus dependent upon the available moisture. The latter difficulty can be overcome by dissolving the chemical and, for example, in the case of salt, applying it as a brine solution. Thus, the use of water solutions to apply the chemicals has been the subject of several test programs in California, North Dakota and in Italy. For example, see the article "Brine Solution Removes Stubborn Ice," by James O. Kyser, Public Works Magazine, January 1971; "Liquid Treatments of Commercial Calcium Chloride in Winter Road Maintenance," by G. E. Scotto, HRB Special Report 115; "Snow and Ice Control in California," by C. E. Forbes, C. F. Stewart and D. L. Spellman, HRB Special Report 115, Page 181.
In order to reduce both the adverse environmental impact and the cost of employing brine or other liquids as well as to reduce the corrosive effect of brine or the like, it is desirable to obtain the maximum degree of softening the frozen water with application of the minimum amount of brine or the like.
One difficulty with prior liquid deicer application techniques is that the liquid has a tendency, particularly when the frozen water layer is hard ice or sleet, to run off the surface without penetrating the frozen water layer sufficiently. This aggravates the pollution problem and wastes the salt or calcium chloride. Another difficulty is poor distribution of the liquid, which tends to gather in pools in low places on the roadway, resulting in too much salt or calcium chloride being concentrated in one location and insufficient amounts in another location. If spray-on type applications are employed to provide even distribution over the surface, the liquid does not provide any suitable mechanical breaking up of the frozen water layer.
It is accordingly an object of the present invention to provide a novel method for applying a deicer liquid to a layer of frozen water on a ground surface which provides for penetration of the deicer liquid into the frozen water layer, and highly efficient mechanical as well as chemical action of the liquid on the frozen water.
It is another object of the invention to provide a novel, efficient and relatively inexpensive apparatus to apply a deicer liquid onto a layer of frozen water on a ground surface in the form of coherent laminar streams of liquid having a turbulent outer layer.
It is another object of the present invention to provide a novel method and apparatus which enable the application of a deicer liquid such as brine to a frozen water layer in a highly efficient manner to promote mechanical breaking of the frozen water layer by the streams of liquid and even and efficient distribution of the deicer liquid onto the frozen water layer, thus enhancing the softening and melting chemical effect of the deicer liquid.
Other objects and the advantages of the present invention will become apparent from the following description of the invention.